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Chess-Nut-Engine/chess-sft-corpus-4x-eval

Chess SFT Eval and Benchmark Held-out evaluation splits and a frozen benchmark for Chess-Nut-Engine/chess-sft-corpus-4x. Every FEN in these files is excluded from generated training data (the blocklist is game-scoped: sibling positions of eval games are excluded too). Frozen from the 4x corpus generation run of 2026-07-06 (generator revision 3cd161b1078cdfa6598fba939f40250072adb524) Benchmark: 13,000 frozen examples across 9 splits; eval splits share the game-scoped blocklist… See the full description on the dataset page: https://huggingface.co/datasets/Chess-Nut-Engine/chess-sft-corpus-4x-eval.

sourceHugging Faceapache-2.0updated 3mo agoView on Hugging Face

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Chess SFT Eval and Benchmark

Held-out evaluation splits and a frozen benchmark for Chess-Nut-Engine/chess-sft-corpus-4x. Every FEN in these files is excluded from generated training data (the blocklist is game-scoped: sibling positions of eval games are excluded too).

—Frozen from the 4x corpus generation run of 2026-07-06 (generator revision 3cd161b1078cdfa6598fba939f40250072adb524)
—Benchmark: 13,000 frozen examples across 9 splits; eval splits share the game-scoped blocklist (182,061 FENs) excluded from the training corpus


Eval examples	13,000
Benchmark examples	13,000
Format	JSONL

Loading

python

from datasets import load_dataset

eval_ds = load_dataset("Chess-Nut-Engine/chess-sft-corpus-4x-eval", "eval_splits")
bench_ds = load_dataset("Chess-Nut-Engine/chess-sft-corpus-4x-eval", "benchmark")

Eval Splits

Split	Description	Examples	Size
`chess960`	Fischer Random positions	500	0.1 MB
`endgames`	Tablebase-backed endgame play	1,500	0.2 MB
`evaluation`	Position assessment	1,500	0.3 MB
`mate`	MATE move-choice examples	1,000	0.1 MB
`openings`	Opening knowledge with ECO holdout	500	0.2 MB
`perception`	Board reading and representation	2,000	0.3 MB
`planning`	Best move, puzzle, and consequence tasks	2,000	1.0 MB
`rules`	Move legality and chess rules	2,000	0.3 MB
`tactics`	Tactical motifs and puzzle labels	2,000	1.0 MB

Frozen Benchmark

Split	Description	Examples	Size
`chess960`	Fischer Random positions	500	0.2 MB
`endgames`	Tablebase-backed endgame play	1,500	0.5 MB
`evaluation`	Position assessment	1,500	0.7 MB
`mate`	MATE move-choice examples	1,000	0.4 MB
`openings`	Opening knowledge with ECO holdout	500	0.3 MB
`perception`	Board reading and representation	2,000	1.5 MB
`planning`	Best move, puzzle, and consequence tasks	2,000	1.4 MB
`rules`	Move legality and chess rules	2,000	1.6 MB
`tactics`	Tactical motifs and puzzle labels	2,000	1.4 MB